Motor driven feed mechanism for feeding a cartridge belt through a channel to an automatic firearm

ABSTRACT

A mechanism for feeding a cartridge belt through a channel to an automatic firearm using a hydraulic motor which directly drives a feed wheel. The mechanism includes a excess pressure relief valve to prevent an overload of the mechanism.

United States Patent [1 1 3,687,002 Miisli et al. Aug. 29, 1972 [54] MOTOR DRIVEN FEED MECHANISM FOR FEEDING A CARTRIDGE BELT [56] 3 References Cited UNHEDSTATESPATENTS m1 'g";::,; f,;';;3, g*g g;" ,;g: 3:3?23212 1311333 Z?fl;.fi..1:::::::::::::111133133 E I land FOREIGN PATENTS OR APPLICATIONS [22] Filed: Oct. 15, 1970 Primary Examiner-Stephen C. Bentley IIo.z A2107 ney-Wender0th, & Ponack 0 F [57] ABSTRACT [3 orelgn Apphcatl'on Pnomy Data A mechanism for feeding a cartridge belt through a Oct. 28, channel to an automatic fiream using a hydraulic motor which directly drives a feed wheel. The [52] US. Cl. ..89/33 E mechanism includes a excess pressure relief valve to [51] Int. Cl ..F41d 9/02 prevent an overload of the mechanism [58] Field of Search..89/33 R, 33 BA, 33 BB, 33 BC,

' 89/33 CA, 33 E 1 Claim, 6 Drawing Figures 29-, A 33 3o- 1 42 1 4/ e 795 Y Patented Aug. 29, 1972 3,687,002

5 Sheets-Sheet 1 ERNST MOSH and LOUIS ZURBUCHEN, Inventor Attorneys Patented Aug. 29, 1972 5 Sheets-Sheet 2 ERNST MOSLI and LOUIS ZURBUCHEN, Inventors Attornryu Patented Aug. 29, 1972 5 Sheets-Sheet 5 ERNST MOSLI, and

LOUIS ZURBUCHEN,

By v

Patented Aug. 29, 1972 3,687,002

Sheets-Sheet 4.

Fig.4 23

I l I ERNST MOSLI and LOUIS ZURBUCHEN,

Inventors Attorneys MOTOR DRIVEN FEED MECHANISM FOR FEEDING A CARTRIDGE BELT THROUGH A CHANNEL TO AN AUTOMATIC FIREARM The invention relates to a mechanism for feeding a cartridge belt through a channel to an automatic firearm, comprising means for protecting the system from overloads.

In a known feed mechanism of this type an electric motor feeds the cartridge belt to the firearm through the channel. If more cartridges are fed into the channel than the gun will accept, the cartridge belt kinks and becomes packed in the channel, stopping the electric motor. In order to prevent the electric motor from a thermal overload, a trip is provided at one point in the channel. The trip opens when the belt starts to kink, and breaks the power supply to the motor. The trip does not function if the belt kinks elsewhere than at the point of location of the trip.

It is the object of the present invention to eliminate this defect.

A mechanism according to the invention for feeding a cartridge belt through a channel to an automatic firearm which mechanism is driven by a hydraulic motor, comprising means for preventing an overloading of the mechanism formed by a relief valve responsive to excess pressure.

The invention is illustrated by way of example in the accompanying drawings in which:

FIG. 1 is an elevational section of a stationary and of a movable part of the belt feeding channel of a belt feed mechanism according to the invention;

FIG. 2 is a section taken on the line IIII of FIG. 1 at major gun elevation;

FIG. 3 is a schematic representation of an armored fighting vehicle equipped with a belt feeding channel and feed mechanism as shown in FIG. 1, illustrating the operation of loading the vehicle with a stock of ammunition;

FIG. 4 is a section on the line IV-IV of FIG. 1;

FIG. 5 is a plan view of a coupling disc in the plane indicated by the line VV in FIG. 4, and

FIG. 6 is a circuit diagram of the hydraulic drive means of the feed mechanism of FIG. 1.

With reference to FIGS. 1 and 3 an ammunition feeding channel 1 includes a portion 2 which is rigidly connected to a casing 4 of a mechanism 3 for feeding a cartridge belt 15. The casing 4 provides a channel 6 for the passage of the belt and is attached to the cover of an ammunition box 7 situated inside the gun turret 9 of an armored fighting vehicle 8. The casing will therefore swing together with the turret 9 when this is rotated about its vertical axis Z to train the gun. Another portion 10 of the channel is attached to a plate 11 which forms part of the cradle carrying the gun 12, and which therefore participates in the movements of the gun about its elevating axis Y.

A disc 13 is provided between the two channel portions 2 and 10. This disc 13 is rotatably mounted in the uppermost part of the vertical portion 2 of the channel and it can rotate in relation to both of the two channel portions 2 and 10. The rotary motions of the channel portion 10 are transmitted to the disc 13 by gear means not shown in the drawing. The transmission ratio provided by these gear means is such that the angle of rotation of the disc 13 in relation to the channel portion 2 is less than the angle of rotation of the channel portion 10 in relation to the channel portion 2.

With reference to FIG. 2 the disc 13 contains a substantially rectangular opening 14 through which the cartridge belt 15 passes. The opening is bounded by a first roller 16 which is mounted on the disc 13 for rotation about an axis parallel to that of the cartridges that pass through the opening 14. A second roller 17 is likewise mounted on the disc 13 in a position so that its axis of rotation is parallel to end faces 18 of the cartridges that are fed through the opening 14. The second roller 17 forms a guide for the cartridges immediately they have passed through the opening 14 in the disc 13. The lower end of a flexible rail 20 which is located substantially adjacent a back wall 19 of the channel portion 2 is rigidly attached to this wall. The upper end of the rail 20 is connected to a rod 21 which is linked to the disc 13. A pin 22 attached to portion 2 of the channel extends across the back of the rail 20 and forms a bearing support.

With reference to FIG. 4 a hydraulic axial cylinder motor 23 is bolted to the casing 4. A rotatable coupling plate 27 is mounted in ball bearings 79 in the casing 4. FIG. 5 shows that this plate contains arcuate slots located on a circle concentric with the axis of the plate. The slots are all of the same length and equidistantly spaced. The shaft 28 of the motor 23 runs in ball bearings 80 in the coupling plate 27 and in ball bearings 81 in the casing 4. A sleeve 29 encircles the shaft 28 and fits into a polygonal opening in the coupling plate 27 for common rotation therewith. A second sleeve 30 encircles the sleeve 29, the two sleeves being splined together. A third sleeve 31 is mounted on ball bearings 82 and encircles the sleeve 30. The third sleeve is positioned inside and keyed to a hub 33 of a feed wheel 32. Recesses 41 machined into the circumference of the sleeve 30 contain spring-loaded rollers 42 that are thus interposed between the two sleeves 30 and 31, the arrangement forming an overrunning clutch of a conventional type. The arrangement will be more readily understood by also referring to FIG. 1. The feed wheel 32 is spider keyed to a plate 34. This plate is held fast on a polygonal part of the shaft 28 so that the feed wheel 32 is driven directly without interposed gearing by the shaft 28 of the motor 23. The teeth 35 of the feed wheel 32 are contained in two radial planes of the shaft 28 and the tips of the teeth 35 move in circular paths to which the longitudinal center plane of the belt channel 6 is a tangent (FIG. 1).

Between a flange 37 of the sleeve 29 and the plate 34 is positioned a ring 36 fitted with centering pins 38 that are parallel to the axis of the shaft 28 and engage bores 39 in the flange 37 of the sleeve 29. Springs 40 which bear on the flange 37 and the ring 36 urge the ring 36 against the plate 34. Hence the spring-loaded ring 36 and the plate 34 together form a slip coupling which transmits a predetermined limited torque from the shaft 28 to the sleeve 29, 30 and the coupling plate 27.

A piston 44 is movable within a bore 46 parallel to the shaft 28 in an end wall of the casing 4. The stroke of the piston 44 is limited by a shoulder 49 separating two portions of different diameter 47, 48 of the bore and by a ring 50 inserted into the bore. A cylindrical extension 51 of the piston 44 containing a slot 52 projects from the bore 47. A pivot pin 53 is placed in a direction normal to the shaft 28 between webs 54 attached to the wall 45 of the casing. The pivot pin 53 carries a two-armed lever 55. One arm of the lever engages the slot 52 in the piston extension 51. The other arm is loaded by the thrust of a spring 57 housed in a cup-shaped sleeve 56 which bearing against the bottom of a recess in the wall 45 of the casing. The piston 44 is biased by the thrust of the spring 57 transmitted by the lever 55 to maintain contact with the shoulder 49.

Another extension 58 of the piston 44 which is coaxial with the extension 51 projects through portion 48 of the bore into one of the slots 43 in the coupling plate 27. The bore portion 48 is sealed from the outside by an O-ring 59. An annular chamber 60 surrounds the extension 58. The chamber 60 is closed by a shoulder in the bore and in conjunction with the bore portion 47 which slidably contains the piston it forms a pressure cylinder 61.

A pin 70 passes into the casing wall 45. A hub 72 of a lever 71 comprising a handle 73 and a cam 74 is pivoted on the pin 70. The cam has a milled face 75 which forms a ramp between two surfaces 76 and 77 that are both parallel to the casing wall 45 but at two different levels in relation thereto. When the lever 71 is in a position of rest as shown in FIG. 4 a projection 78 on the arm 55a of lever 55 bears on the face 76 of the lever 71.

With reference to FIG. 6, the hydraulic circuit comprises a pump 83 which feeds the hydraulic motor 23 with fluid from an oil reservoir 85 through a pipe 24 and a valve 25. Since the pump 83 normally runs continuously, whereas the valve 25 to the hydraulic motor 23 is opened only when the firing button of the gun is depressed, the pipe 24 communicates via a return valve 84 with the reservoir 85 so long as the firing button is not touched. The pipe 24 is also connectable to the reservoir by an excess pressure relief valve 26. The hydraulic cylinder 61 is connected by a pipe 62 to a two-way valve 63 which in turn is connected by a pipe 64 to the pipe 24 connecting the pump 83 to the valve 25. The winding 65 of an electromagnet for operating the valve 63 is connected by two electrical lines 66, 67 to the two poles of a voltage source 68. Line 67 contains a switch 69. The switch 69 is located on the outside of the turret 9, as shown in FIG. 3.

The manner in which the described system functions is as follows.

Before the ammunition box 7 is filled a gunner standing on the deck of the armored vehicle 8 alongside the gun turret 9 operates the switch 69 to apply voltage to the magnet winding 65 of the valve 63 and thereby to establish communication between the two pipes 64 and 62. The hydraulic oil which now flows from the pipe 24 into the annular chamber 60 in the cylinder 61 operates to move the piston 44 against the ring 50, causing the lever 55 (as seen in FIG. 4) to be deflected counterclockwise about its pivot pin 53 to compress the spring 57 and to withdraw the piston extension 58 from the slot 43 in the coupling plate 27. One end of the cartridge belt is now inserted into the entry of channel 10, in the side of the gun turret 9, and pushed over the roller 16 and through the channels 2 and 6 into the ammunition box 7 in which it is stacked by a second gunner. The cartridges in the belt moving along the channel 6 in the casing 4 engage between the teeth 35 of the feed wheel 32 causing the wheel and hence the sleeve 31 to rotate in the clockwise direction (in FIG.

1). The rotation of the sleeve 31 is transmitted by the spring loaded rollers 42 to the sleeve 36 and by the latter to the sleeve 29 which moves in synchronism with the plate 34 which is likewise driven by the feed wheel 32 and the shaft 28 of the motor which idles, not being hydraulically pressurized.

When the ammunition box is full the magnet winding of valve 63 is again disconnected from the voltage source 68 and communication between the cylinder 61 and the hydraulic supply pipe 24 is thus again interrupted. The piston 44 is therefore returned into contact with the shoulder 49 by the thrust of the spring 57 on the lever 55. Consequently the extension 58 moves towards the coupling plate 27 and enters one of the slots 43. The rotating plate 27 is thus intercepted by the extension 58 and the feed wheel 32 is stopped. The last cartridge in the belt 15 will now be in firing position in the gun 12.

As an alternative the piston 44 and its extension 58 may be operated by a gunner from inside the turret 9. When the lever 71 is deflected the projection 78 on the lever 55 rides from the face 74 up the ramp 75 onto the face 77, causing the lever 55 to be tilted counter clockwise (in FIG. 4) and the piston extension 58 to be withdrawn from the slot 43 it had engaged in the coupling plate 27. When the lever 71 is deflected back again the projection 78 is pushed into contact with the face 76 of the lever by the thrust of the spring 57, the lever 55 being thus tilted in the clockwise direction, pushing the piston extension 58 against the coupling disc 27 and into one of the slots 43.

Simultaneously with the opening of fire by operation of the trigger (not shown) the valve 25 is opened and the valve 84 closed, hydraulic oil being supplied to the motor 23 which is thus started. The motion of the plate 34 which rotates together with the shaft 28 of the motor is transmitted by the ring 36 and the pin 38 to the sleeve 29 and hence to the coupling disc 27. The feed wheel 32 which is likewise driven by the plate 34 rotates the sleeve 31 in the clockwise direction (in F IG. 1) at the same speed as the sleeve 29. At the end of a part revolution corresponding to the length of a slot 43 the coupling disc 29 is intercepted by the piston extension 58 and is thus stopped, whereas the feed wheel 32 and the sleeve 31 continue to rotate.

The feed mechanism 3 propels the belt 15 which had been deposited in loops in the box 7, into the channel 6 whence it is drawn into the gun by the recoil energy of the breech mechanism (not shown) of the gun 12. When at the end of a burst of fire the breech mechanism is intercepted and no more cartridges are withdrawn from the channel 10, the motor 23 nevertheless continues to run and the feed wheel 32 therefore forces more cartridges into the channel 2. This causes the belt 15 which had so far remained substantially fully extended to kink at some of the joints and the cartridges to be packed into the available space in the channel 1.

When the channel 1 has thus been fairly tightly packed, i.e. when for example, six more cartridges have been forced into the channel, the resistance due to the packing of the cartridges prevents the motor 23 from continuing to turn the feed wheel 32. The motor therefore stops. At the end of a given period of delay after the cessation of tire the supply of hydraulic oil to the motor 23 is stopped. The weight of the additionally propelled cartridges which now rests on a tooth 35 of the feed wheel 32 causes the latter to rotate together with the sleeve 31 (in FIG. 1) in the clockwise direction. The spring loaded rollers 42 cause the sleeve 30 to be entrained in the same direction of rotation until the coupling plate 27 which is fast with the sleeve 29 is stopped by the piston extension 58 striking the end of the slot 43 into which it projects. At the same time the rollers 42 stop the sleeve 31 together with the feed wheel 32. This backwards rotation of the feed wheel 32 permits the portion of the belt 15 supported by the wheel to drop back towards the ammunition box 7 for instance by a distance equal to the diameter of one cartridge. The tightly packed belt in the channel 1 is thus somewhat loosened. This loosening is necessary for the following reason:

When the gun 12 together with the channel and the disc 13 is elevated about its elevating axis Y during a firing interval the faces 18 of the rear ends of the cartridges which are supported by the rail 20 that arches into the channel 2 are pushed more tightly together, as will be understood by studying the drawing in FIG. 2. Without this prior loosening of the belt considerable compressive forces might be generated where the additionally fed cartridges are already packed tightly against the walls of the channel, and these forces could lead to the channel being ruptured.

The additional cartridges which are contained in the channel 1 between the feed mechanism 3 and the gun 12 in excess of those that are present when the belt is extended whenever there is a pause in the firing, form a store of ammunition upon which the gun 12 can draw until the feed mechanism 3 becomes fully operative after firing has been recommenced.

If the firing gun 12 should withdraw fewer cartridges from the channel 10 than the feed mechanism 3 feeds into the channel from the ammunition box 7, then the rate of cartridge supply is regulated as follows: When the belt 15 offers a predetermined resistance due to packing of the cartridges in the channel 2 the motor 23 of the feed mechanism 3 automatically stops. However, since the gunner has kept his finger on the firing button of the gun the valves 25 and 84 remain in their operative positions (contrary to the positions shown in FIG. 6). The build-up of pressure in the system when the pump 83 continues to run is limited by the excess pressure relief valve 26 to the maximum permissible system pressure. The motor 23 therefore does not restart until the gun 12 has withdrawn sufficient cartridges from the channel 1 to reduce the resistance to feeding.

We claim:

1. A mechanism for feeding a cartridge belt through a channel to an automatic firearm driven by a hydraulic motor having a shaft, comprising means for preventing an overloading of the mechanism having a relief valve responsive to excess pressure, a feed wheel driven by said hydraulic motor for feeding the cartridge belt having a direct driving connection between said feed wheel and said shaft, a slip coupling between said shaft and a coupling disc having arcuate slots disposed in a circle engageable by an axially movable pin, an overrunning clutch between said feed wheel and said coupling disc so that when said feed wheel is driven said coupling disc is entrained in the feeding irectio by said slip coup mg until intercepted by sal pm strl ing one end of the slot into which it projects, and so that when said motor stops said feed wheel can rotate backwards under load until said pin strikes the other end of said slot. 

1. A mechanism for feeding a cartridge belt through a channel to an automatic firearm driven by a hydraulic motor having a shaft, comprising means for preventing an overloading of the mechanism having a relief valve responsive to excess pressure, a feed wheel driven by said hydraulic motor for feeding the cartridge belt having a direct driving connection between said feed wheel and said shaft, a slip coupling between said shaft and a coupling disc having arcuate slots disposed in a circle engageable by an axially movable pin, an overrunning clutch between said feed wheel and said coupling disc so that when said feed wheel is driven said coupling disc is entrained in the feeding direction by said slip coupling until intercepted by said pin striking one end of the slot into which it projects, and so that when said motor stops said feed wheel can rotate backwards under load until said pin strikes the other end of said slot. 